1. Field of the Invention
The present invention relates to organosilicon compounds having hydroxyl and carboxyl groups or cyano group which are effective stabilizers for aqueous silicates, silica sols and other silica containing water, such as boiler water, antifreezer and coolant solutions.
2. Descriptions of the Prior Art
It is well known that alkali metal silicates are effective metal corrosion inhibitor. It has therefore been desirable to use alkali metal silicates in antifreezer and coolant formulations. However, antifreezer and coolant compositions containing such silicates generally have the tendency to gel or form precipitates during the storage or after prolonged use at elevated temperatures. Thus, it has been previously proposed to use a stabilizer to prevent the gelation of the alkali metal silicates in the antifreezer compositions so that the silicates could be more persistent in their corrosion inhibiting properties.
A number of organosilicon compounds and organosilicon polymers or organosilicon copolymers with organic polymers such as polyethylene oxides have been known to be effective as the stabilizers for alkaline metal silicates corrosion inhibitor additives in antifreezer/coolant compositions.
U.S. Pat. Nos. 4,462,921, 4,287,077 and 4,485,025 disclose the use of organosilicon polymers or copolymers with organic polymer as the stabilizers for this purpose. Since the organic polymers have limited solubility in aqueous systems or in glycols, they are usually coupled with hydrophilic groups such as carboxylic acids, polyethers etc. Nonhydrolyzable linkage between the hydrophilc groups and organosilicon polymers can be obtained by hydrosilylation reaction. (Y. Lukevit M. G. Voronkov, "Organic Insertion Reactions of Group IV Elements", Consulant Bureau, New York, 1966). Unfortunately the reaction requires expensive platinum catalyst. In U.S. Pat. No. 4,514,315, there is disclosed that an aqueous or alcohol solution of a alkylene silane grafted polyether provides an aluminum corrosion inhibitor effect.
Organotrialkoxysilanes have been used in antifreeze compositions to improve the anti-gel characteristics of those compositions. U.S. Pat. Nos. 3,198,820, 3,265,623 and 3,312,622 disclose the use of organic acid silane compounds for this purpose. U.S. Pat. Nos. 3,203,969 and 3,248,329 also disclose the use of aminosilane compounds for this purpose. In U.S. Pat. Nos. 4,333,843 and 4,367,154, there is disclosed that the self life or gelation resistance of single phase aqueous glycol or glycol ether compositions can be improved by the addition to the glycol compositions of an effective amount of the hydrolyzate of organophosphorous-silicon compounds.
Pines et al described another system in U.S. Pat. Nos. 3,337,496 and 3,341,469 that was found useful for inhibiting corrosion in aqueous alcohol compositions. It consisted of a mixture of hydroxyalkylsilanes or hydroxyalkylether silanes and a silicate. The materials are stated as being remarkably soluble in aqueous liquids. The hydroxyalkylsilanes and hydroxyalkylether silanes were easily prepared by hydrolysis of the corresponding epoxyalkylsilanes in the presence of base. ##STR4##